Read directories recursively with Node.js

readdir_recursive.js

var fs = require('fs')
  , async = require('async')
  , _ = require('underscore');

/**
 * Utility - for functions that do not belong anywhere
 *
 * @namespace - utility
 */
var utility = exports;

utility.readdirRecursive = function(dirPath, callback) {
  function mapPath(filePath, mapCallback) {
    return fs.stat(filePath, function(err, stats) {
      if (err) {
	return mapCallback(err, filePath);
      } else {
	if (stats.isFile()) {
	  return mapCallback(null, filePath);
	} else if (stats.isDirectory()) {
	  return utility.readdirRecursive(filePath, mapCallback);
	} else {
	  return mapCallback(null, filePath);
	}
      }
    });
  };

  fs.readdir(dirPath, function(err, files) {
    if (err) {
      return callback(err, null);
    } else {
      var fullFilePaths = _.map(files, function(filePath) {
	return dirPath + '/' + filePath;
      });
      return async.map(fullFilePaths, mapPath, function(err, mappedPaths) {
	return callback(err, _.flatten(mappedPaths));
      });
    }
  });
};